The present invention relates to a structure of a vehicular meter unit, and more particularly to an installation structure of the vehicular meter unit that improves its productivity and various performances.
Various vehicular meter units have been proposed and in practical use. FIG. 6 shows a conventional installation structure of a vehicular meter unit. As shown in FIG. 6, an analog meter unit 101 of the vehicular meter unit is constituted by a movement 101A, a shaft 101B, a pointer 101C and a dial plate 101D. A bottom surface of the movement 101A is fixed to a circuit board 102 by means of a plurality of installation screws 103A. A top surface opposite to the bottom surface of the movement 101A is fixed to a light guiding plate 104 laminated with the dial plate 101 D by means of screws 103B extending through holes 108. A protection cover 105 covers a bottom side of the movement 101A, and a front cover 106 covers the dial plate 101D and the pointer 101C. The light guiding plate 104 receives light from a lamp 107.
However, since this fixing structure is arranged to connect the movement with both the circuit board and the light guiding plate by means of screws, there are problems to be solved such that it requires a large number of the parts for the assembled unit and a lot of time for assembly operation steps thereof. Further, in case of a meter unit employing a continuous dial plate including a plurality of meters such as a speedometer (vehicle speed meter), a tachometer (engine rotation speed meter), a fuel gauge and a water temperature gauge, characters and scales thereof are printed on the continuous dial plate, and the movements of the respective meters are fixed to both the circuit board and the continuous dial plate. Further, the dial plate is generally made of polycarbonate having a larger thermal expansion characteristic and the circuit board is generally made of glass-epoxy or phenol resin having a small thermal expansion characteristic. Therefore, there is a possibility that the dial plate will be deformed with respect to the circuit board due to the thermal expansion characteristic of the dial plate larger than that of the circuit board. More particularly, under high temperature condition, the dial plate having a relatively small rigidity will be deformed with respect to the circuit board, or a shaft hole of the dial plate will be deformed so as to interfere the operation of the pointer shaft. Further, there is a possibility that the deformation of the dial plate will apply an undesired load to the movement so as to cause electrical troubles as to the movement. More specifically, the undesired load will be applied to a soldering portion of a connecting pin which electrically connects the movement and the circuit plate, so that the soldering portion may receive a stress to cause electrical contact-failure. Additionally, since the conventional meter unit has been arranged to be fixed to the dial plate laminated with the light guiding plate by means of screws, the screws will degrade the illuminating characteristic and the external appearance of the dial plate.
It is an object of the present invention to provide an improved vehicular meter unit which solves the above-mentioned problems while improving an installing easiness of a meter to a dial plate.
A vehicular meter unit according to the present invention is arranged such that an analog meter is not directly connected to a dial plate to avoid influence due to thermal deformation of the dial plate. That is, the vehicle meter unit according to the present invention is arranged to comprise a lower housing, a circuit board fixed to the lower housing and an analog meter fixed only to said circuit board.
More specifically, another aspect of the present invention resides in a vehicular meter unit which comprises a lower hosing, a circuit board, a dial plate and an analog meter. The lower housing includes a top plate and a peripheral wall perpendicularly extending from a periphery of the top plate. The circuit board is fixed to a free periphery of the lower housing peripheral wall. The dial plate is installed to the top plate of the lower housing. The analog meter is fixed only to the circuit board, a shaft of the analog meter penetrates the dial plate without contacting with the dial plate.